Nonorthogonality of eigenstates is a fundamental characteristic of non-Hermitian systems. It is expected that nonorthogonality-induced effects could be enhanced in the vicinity of the exceptional points (EPs) where the multiple eigenstates coalesce into one. Here, focusing on the wave-packet motions in non-Hermitian systems, we find that a wave packet near the EPs could exhibit new types of Zitterbewegung- (ZB-) like motion arising from the nonorthogonality of eigenstates. The observed ZB-like motion of a wave packet centered around a single eigenstate contradicts the notion that ZB motion only occurs for a wave packet centered around a superposed state. We further show the existence of a ZB-like motion in the form of an interesting helical trajectory of the wave packet on the incident plane, stemming from the imaginary part of group velocities. These exotic ZB-like motions may provide great insight into nonorthogonal eigenstates and complex eigenfrequencies of non-Hermitian systems.

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• Optical coherence
• Photonics
• Non-Hermitian systems